Centrifuge for separating massecuite

Abstract

A centrifuge for separating massecuite into solid and liquid fractions has a rotatable drum which includes a circumferential wall having a small and uniform thickness, and top and bottom walls. Sieves for separating massecuite into its constituent liquid and solid fractions are located in an inner chamber which is bounded by the walls of the drum. At least two rows of holes are formed in the circumferential walls through which the liquid fraction is discharged whereas the solid fraction retains in the inner chamber. The drum is reinforced in the regions of the top and bottom walls, for instance by means of two ring members which are fitted on the circumferential wall adjacent to the top and bottom walls. On the other hand, it can be reinforced by means of inclination of the top wall and/or the bottom wall to a horizontal plane. It is also possible to provide the reinforcing ring member adjacent to the bottom wall and to incline the top wall of the drum, and vice versa.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: 
     
       1. A centrifuge for separating massecuite into solid and liquid fractions, comprising a rotatable drum having a circumferential wall, a top wall and a bottom wall together bounding an inner chamber, said circumferential wall being unworked and having a small and uniform thickness, said circumferential wall being subjected in operation to tangential stresses in the regions of said top wall and bottom wall resulting from bending moments generated in the latter; sieve means in said inner chamber and arranged for separating massecuite into its constituent solid and liquid fractions; means for discharging the liquid fraction from said inner chamber and retaining the solid fraction in the latter, including two rows of holes one of which is arranged adjacent to said bottom wall whereas the other row is formed adjacent to said top wall; means for reinforcing said drum cooperating with said circumferential wall but located only adjacent to said top and bottom walls, respectively, so as to reduce said tangential stresses in the regions of said top wall and bottom walls whereby at least a major part of said circumferential wall remains free of said reinforcing means, and the entire circumferential wall remains having said small and uniform thickness, said reinforcing means being two ring members fitted on said circumferential wall of said drum adjacent to said top and bottom walls, respectively, and each spaced from said bottom and top walls, respectively, by a distance which is equal to substantially between 10 and 15% of the inner diameter of said drum; and means for rotating said drum. 
     
     
       2. A centrifuge as defined in claim 1, wherein said ring members are rings which are pressed on said circumferential wall. 
     
     
       3. A centrifuge as defined in claim 11, wherein each of said ring members has a cross-section whose dimensions are defined in accordance with the formula:   (b·S.sub.3)/t.sup.3/2 =20-45     wherein b is a height of each of the rings, S 3  is a thickness of each of the rings, and t is a thickness of said circumferential wall of said drum.   
     
     
       4. A centrifuge as defined in claim 1, wherein said circumferential wall has a central region located between said top and bottom walls, said discharging and retaining means further including two additional such rows of holes arranged in said central region of said circumferential wall, said reinforcing means further including an additional such reinforcing ring member fitted on said circumferential wall between said additional rows of holes. 
     
     
       5. A centrifuge as defined in claim 4, wherein said drum has a predetermined inner diameter, said additional rows of holes being spaced from one another by a distance which is smaller than 15% of the inner diameter of said drum. 
     
     
       6. A centrifuge as defined in claim 4, wherein said discharging and retaining means includes two further such rows of holes arranged in said central region of said circumferential wall and spaced from said additional holes, said reinforcing means further including a further such ring member fitted on said circumferential wall between said further rows of holes. 
     
     
       7. A centrifuge as defined in claim 6, wherein said drum has a predetermined inner diameter, said further ring member being spaced from said additional ring member by a distance which is equal to one-fifth part of the inner diameter of said drum. 
     
     
       8. A centrifuge for separating massecuite into solid and liquid fractions, comprising a rotatable drum having a circumferential wall, a top wall and a bottom wall together bounding an inner chamber, said circumferential wall being unworked and having a small and uniform thickness, said circumferential wall being subjected in operation to tangential stresses in the regions of said top wall and bottom wall resulting from bending moments generated in the latter; sieve means in said inner chamber and arranged for separating massecuite into its constituent solid and liquid fractions; means for discharging the liquid fraction from said inner chamber and retaining the solid fraction in the latter, including two rows of holes one of which is arranged adjacent to said bottom wall whereas the other row is formed adjacent to said top wall; rings for reinforcing said drum, fitted on and cooperating with said circumferential wall but located only adjacent to said top and bottom walls, respectively, so as to reduce said tangential stresses in the regions of said top wall and bottom walls whereby at least a major part of said circumferential wall remains free of said reinforcing rings, and the entire circumferential wall remains having said small and uniform thickness; and means for rotating said drum. 
     
     
       9. A centrifuge as defined in claim 8, wherein said drum is swingably suspended to a supporting structure; and further comprising means for swingably suspending said drum, to the supporting structure. 
     
     
       10. A centrifuge as defined in claim 8, wherein said sieve means includes a supporting sieve and a fine-meshed sieve. 
     
     
       11. A centrifuge as defined in claim 8, wherein said circumferential wall has a predetermined thickness, said top wall having a thickness which 1 to 5 times exceeds the thickness of said circumferential wall. 
     
     
       12. A centrifuge as defined in claim 8, wherein said circumferential wall has a predetermined thickness, said bottom wall having a thickness which 2 times exceeds the thickness of said circumferential wall. 
     
     
       13. A centrifuge as defined in claim 8, wherein said drum has a predetermined inner diameter, said circumferential wall having a thickness which is smaller than one-hundredth part of the inner diameter of said drum. 
     
     
       14. A centrifuge for separating massecuite into solid and liquid fractions, comprising a rotatable drum having a circumferential wall, a top end wall and a bottom end wall together bounding an inner chamber, said circumferential wall being unworked and having a small and uniform thickness, said circumferential wall being subjected in operation to tangential stresses in the regions of said top end wall and bottom end wall resulting from bending moments generated in said end walls; sieve means in said inner chamber and arranged for separating massecuite into its constituent solid and liquid fractions; means for discharging the liquid fraction from said inner chamber and retaining the solid fraction in the latter, including two rows of holes one of which is arranged adjacent to said bottom end wall whereas the other row is formed adjacent to said top end wall; means for reinforcing said drum cooperating with said circumferential wall but located only adjacent to said top and bottom end walls, respectively, so as to reduce said tangential stresses in the regions of said top end wall and bottom end walls whereby at least a major part of said circumferential wall remains free of said reinforcing means, and the entire circumferential wall remains having said small and uniform thickness, said reinforcing means including a ring member which is fitted on said circumferential wall adjacent to one of said end walls and reinforces said drum in the region of the latter, the other of said end walls being outwardly inclined so as to form a part of said reinforcing means which reinforces said drum in the region of said other end wall; and means for rotating said drum. 
     
     
       15. A centrifuge as defined in claim 14, wherein said one end wall is formed by said bottom end wall, and said other end wall is formed by said top end wall. 
     
     
       16. A centrifuge as defined in claim 14, wherein said other end wall is conical. 
     
     
       17. A centrifuge as defined in claim 14, wherein said other end wall extends at an angle to a horizontal plane which exceeds 10°. 
     
     
       18. A centrifuge as defined in claim 14, wherein said drum has a predetermined inner diameter, said ring member being spaced from said one end wall by a distance which is equal to substantially between 10% and 15% of the inner diameter of said drum. 
     
     
       19. A centrifuge for separating massecuite into solid and liquid fractions, comprising a rotatable drum having a circumferential wall, a top wall and a bottom wall together bounding an inner chamber, said circumferential wall being unworked and having a small and uniform thickness, said circumferential wall being subjected in operation to tangential stresses in the regions of said top wall and bottom wall resulting from bending moments generated in the latter; sieve means in said inner chamber and arranged for separating massecuite into its constituent solid and liquid fractions; means for discharging the liquid fraction from said inner chamber and retaining the solid fraction in the latter, including two rows of holes one of which is arranged adjacent to said bottom wall whereas the other row is formed adjacent to said top wall; means for reinforcing said drum cooperating with said circumferential wall but located only adjacent to said top and bottom walls, respectively, so as to reduce said tangential stresses in the regions of said top wall and bottom wall whereby at least a major part of said circumferential wall remains free of said reinforcing means, and the entire circumferential wall remains having said small and uniform thickness, said top wall of said drum being outwardly inclined to a horizontal plane at a first angle and said bottom wall of said drum being outwardly inclined to the horizontal plane at a second angle so as to form said reinforcing means; and means for rotating said drum. 
     
     
       20. A centrifuge as defined in claim 19, wherein said top and bottom walls of said drum are conical. 
     
     
       21. A centrifuge as defined in claim 19, wherein said second angle exceeds 5°. 
     
     
       22. A centrifuge as defined in claim 19, wherein said first angle is at least equal to said second angle. 
     
     
       23. A centrifuge as defined in claim 22, wherein said first angle exceeds said second angle.